Amunix, Inc.

Microprotein Technology

Microproteins are small protein domains of 15-60AA with a multi-disulfide core, derived from the venom of animals. The disulfide rich core in microproteins replaces the much larger hydrophobic core that typical globular proteins require for folding.

This single replacement of a large number of hydrophobic amino acids with a small number of disulfides results in a protein that is much smaller, more hydrophilic (less prone to aggregation and non-specific binding), more resistant to proteases and heat. In addition, because hydrophobic residues are anchor residues that are required for MHC presentation, microproteins have a lower density of T-cell epitopes, thus reducing the potential for an immune response. For example, the Tepitope score of typical microproteins is more than 700-fold lower than that of various approved non-human protein pharmaceuticals. These properties make microproteins attractive starting points for the design of protein pharmaceuticals.

Animal venoms are a potential rich source of pharmaceuticals containing a multitude of biologically active proteins and peptides. Many of these compounds are small proteins of 8-70AA containing a multi-disulfide core that have evolved to bind their protein targets with unprecedented affinities and selectivities. To date, over 2800 compounds have been isolated and characterized from the venom of snakes, scorpions, spiders, marine snails, and sea anemones. The targets modulated by native venom microprotein include ion channels GPCRs, integrins, and a variety of enzymes. The use of microproteins as pharmaceuticals has already been proven by the approvals of Ziconotide (Prialt®), an ion channel blocker for pain indications, and Desirudin (Iprivask®), a derivative of leech hirudin for anticoagulation. However, the target specificity, activity and serum half-life of native microproteins typically require optimization to serve as effective pharmaceuticals.

The first therapeutic program at Amunix to leverage the microprotein technology focuses on the targeting of ion channels. Ion channels are involved in many cellular functions and have been implicated in numerous pathological conditions, including neuronal, cardiovascular, respiratory, metabolic, immunological and oncology indications. Their importance in disease is underscored by the fact that over 13% of prescribed drugs target only a fraction of this critical class of proteins. A key advantage of the microprotein technology in this application is that many of the naturally occurring venom microproteins have existing ion channel modulating activity. This provides multiple excellent starting points for the creation of lead candidates where the activity only needs to be tuned rather than created de novo. This is allowing Amunix to quickly develop specific and high affinity inhibitors for ion channels that have been implicated in a variety of diseases. Additionally, with the large diversity of natural activities of the venom microproteins this approach is expandable to other targets like GPCR receptors, integrins and enzymes.

Amunix’s proprietary technology starts with the selection and library generation of folded near-natural microprotein variants. These libraries are then screened for the desired biological activity. The selected microprotein variants can be rapidly scaled up and manufactured in E. coli at high yields. This offers rapid progression from lead candidate identification to pre-clinical studies and human trials. The inherent properties of microproteins cause the lead candidates to already possess numerous favorable properties for a pharmaceutical. The small size and hydrophilic nature of microproteins means that they are highly soluble and can be formulated to concentrations that far exceed that of other biological pharmaceuticals. Additionally, the multi-disulfide core makes microproteins exceptionally heat stable, which increases shelf-life and allows for convenient liquid formulation.

The combination of XTEN and microprotein technologies in a single product can offer both high target selectivity and tunable serum half-life extension.